It is known that hydrogen can be generated by exothermically reacting water and elemental metal or a metal hydride. The reaction involves producing hydrogen gas (H.sub.2) and an oxide of the metal.
It is also known that a high temperature, high pressure plasma jet can be derived by applying a discharge voltage between spaced electrodes along a capillary passage having a dielectric wall with ionizable material thereon. In response to the discharge, the ionizable material is ablated from the wall to produce a plasma discharge in the capillary passage, i.e., a passage having a length to diameter ratio of at least 10:1. Because of the capillary nature of the passage, the impedance of the discharge between a pair of electrodes at opposite ends of the passage is relatively high, such as 0.1 ohms, to facilitate matching of the discharge load to a power supply that derives the discharge voltage. The power in the discharge can be controlled by shaping a pulse output of the power supply. This high pressure plasma source has been used for propelling projectiles, generally initially located in a barrel downstream of the passage open end.
It is also known to provide a cooling medium between an outlet of the plasma source and the projectile initial location. The cooling medium includes elements that are vaporized by the plasma to serve as a fuel source for propelling the projectile through the barrel.
To maximize the velocity of the projectile as it leaves the barrel, it is preferable for the pressure in the barrel to remain relatively constant, even though the barrel length behind the projectile effectively increases as the barrel moves through the barrel. To provide a constant pressure in the barrel behind the projectile as the projectile is being accelerated through the barrel, the power supply pulse is preferably shaped so that the power in the discharge increases substantially linearly as a function of time as the projectile is being accelerated. This linear increase of the power occurs while the projectile moves through about the first third of the barrel.